This invention relates to a device which is a part of a packaging machine adapted to form bags from an elongated film and serves to poke articles to be packaged to thereby push them into a bag being formed without clogging up the narrow passage of a chute through which they are passed.
Japanese Utility Model Publication Jikko 3-1362 disclosed a packaging machine of the type adapted to form an elongated film into a tubular shape while pulling it out of a roll and to transport it downward, to drop articles to be packaged into it after a lower edge part of this tubular form is sealed and to seal its upper edge part to form a packaged product with the articles sealed inside. As shown in FIG. 9, this packaging machine includes a former 6 having a sloped film guide 6a extending at its back part such that an elongated film F pulled out of a roll is folded, as it slides over this film guide 6a, into a tubular form F' with its both side edges overlapping each other. Thereafter, these mutually overlapping side edges are sealed together by means of a longitudinal sealer (not shown) and the tubular form F' is also sealed transversely by means of a transverse sealer (not shown) to form a packaged bag. A chute 7 with a conical part is disposed above the former 6, and after articles to be packaged are thrown through this chute 7 into a packaging bag with its bottom edge part sealed, its upper edge part is also sealed by the transverse sealer over a seal area and the film is cut transversely to obtain a desired packaged product.
With a packaging machine of this type, articles which have been dropped into the chute 7 sometimes get stuck therein, depending on their shapes and sizes, failing to fall into the bag being formed. If this happens, a product with less than the desired amount of articles may be produced and if the articles which became stuck in the previous cycle of operation also drop, a product with more than the desired amount may be produced. In order to prevent such an occurrence, a device herein referred to as a poker is sometimes utilized to forcibly push down the articles stuck in the chute. As shown in FIG. 9, such a poker may be placed above and at the back of the former 6, comprising a generally L-shaped arm member 94 having a first part 94b extending upward from its base part 94a when it is at its initial position (shown by solid lines in FIG. 9) and a second part 94c extending forward from the upper end of the first part 94b. A driving means 92 such as a motor is provided for causing this arm member 94 to undergo a reciprocating rotary motion such that, as the arm member 94 is rotated in the forward direction from its initial position, the tip 94c' of the second part 94c will enter the interior of the chute 7 as shown by dotted line in FIG. 9, thereby reliably causing any articles stuck therein to drop into the bag which is being formed below.
If the arm member 94 is made of a synthetic resin material, however, forces inside tend be concentrated at its bend between the first and second parts 94b and 94c, deforming the arm member 94 as it swings back and forth many times periodically, and this makes it difficult for the tip 94c' to reliably come to the bottom center of the chute 7. If the arm member 94 becomes significantly deformed, its tip 94c' may strike the inner surface of the chute 7 and it may even break due to the material fatigue.
If the arm member 94 is made of a metallic material, on the other hand, it will be too heavy and the load on its driving means 92 becomes undesirably large. If the articles to be packaged are a food material, furthermore, a metal detector is sometimes provided for detecting any metallic substance which may be mixed in, but the use of such a metal detector will not be possible if the poker comprises a metallic arm member.
It may be thought of using an arm member made of a synthetic resin material containing reinforcing fibers. Synthetic resin materials containing reinforcing fibers are both light and strong but the reinforcing fiber materials are easily peeled off and there arises a problem of hygiene if the articles to be packaged are a food material.
Moreover, there is a problem of layout. As shown in FIG. 9, the poker is generally positioned behind the former 6 and the chute 7, disposed such that the arm member 94, initially standing straight upward above and behind the former 6, rotates forward to send its second part 94c into the interior of the chute 7. In order to effectively remove the jam in the chute and reliably cause the articles remaining in the chute 7 to drop into the bag being formed below, however, it is preferable that the tip 94c' of the second part 94c should pass near the back edge part 7c of the upper opening of the chute 7 as indicated by dotted line X1 and enter the interior of the chute 7, and further that the tip 94c' should reach the bottom center of the conical part of the chute 7 as shown by dotted line X2. Thus, if this movement of the arm member 94 is to be accomplished by a simple rotary motion around its base part 94a, its center of rotation e must be on the line y which perpendicularly bisects the line segment x connecting the positions of the tip 94c' when the second part 94c of the arm member 94 is as shown at X1 and X2. As described above, however, the former 6 has its film guide 6a extending backward, and the base part 94a must be disposed so as not to interfere with the operation of the film guide 6a. If the former 6 is adapted to produce relatively narrow bags and hence its film guide 6a is relatively small, it may not be very difficult to place the center of rotation e on the line y as defined above near the chute 7. If the former 6 is adapted to produce wider bags and its film guide 6a extends significantly, as shown in FIG. 9, it becomes necessary to place the center of rotation e fairly far away from the chute 7. This means that the first part 94b of the arm member 94 must be quite long and this makes the entire arm member 94 heavier, and hence that the load on its driving means 92 increases, requiring a larger motor and making its high-speed operations difficult.